David Cameron has vowed to keep pushing for a "robust response" against the Syrian regime despite his crushing Commons defeat.

The Prime Minister said it was a "regret" that he had been unable to rally support for military action in Syria after last week's chemical attack in Damascus.

But he promised to respect the will of Parliament and confirmed the involvement of UK troops was completely off the table because of MPs' strong opposition.

"I think it's important we have a robust response to the use of chemical weapons and there are a series of things we will continue to do," Mr Cameron said.

"We will continue to take a case to the United Nations, we will continue to work in all the organisations we are members of - whether the EU, or Nato, or the G8 or the G20 - to condemn what's happened in Syria.

"It's important we uphold the international taboo on the use of chemical weapons."

Explaining his decision to oppose the Government's motion, Labour leader Ed Miliband told Sky News: "What I wasn't willing to do was have a rush to war, a rush to conflict without clearly going through the right processes.

"Why is this important? because if you’re going to engage in conflict you got to make sure it’s done on a legitimate basis. We don’t have to look far back in our history to understand that," he added.

"Iraq happened under my party. I'm determined we learn the lessons of Iraq."

Image:UN inspectors in Syria are wrapping up their investigation

Nick Clegg said in a letter to LibDems that there are "no easy answers" in the debate, and that the Government "will continue to work actively to build the diplomatic chances for peace".

The intelligence report blamed Syria's government for the attack with "high confidence" and said it was "highly unlikely" the outrage was a ruse plotted by rebels, as the regime has claimed.

The report said that 1,429 people were killed in the atrocity including 426 children, adding the assessment was based on "multiple" streams of intelligence.

Amid some concern that the Commons vote might strain relations with the US, Mr Cameron spoke to Mr Obama, who said said he respected why the PM went to Parliament.

Earlier, the White House had insisted Britain remained "one of our closest allies and friends" and promised the US would continue to communicate with No10 over Syria.

Asked about the relationship with the US, Mr Miliband said: "Should the British government take its own view about what is right? The answer is yes. Will that sometimes involve disagreeing with the United States? Yes, quite conceivably."

As UN inspectors finished their investigation into the alleged chemical attack, some nations voiced support for a military action.

The Turkish foreign minister, Ahmet Davutoglu, said intelligence gathered in Ankara left "no doubt" that the Assad regime was responsible for the chemical attack. Turkey has said it would be ready to take part in any international action against Syria.

French president Francois Hollande also made clear he would be ready to go ahead without Britain as he insisted all options are still on the table.

Video:Syria Vote: Osborne Backs Cameron

Stressing the need for "proportional and firm action", he said: "The chemical massacre of Damascus cannot and must not remain unpunished."

However, Vladimir Putin's aide Yuri Ushakov is reported to have said: "We wouldn't want, of course, for the situation to be getting close to when one country or a group of countries would indict, judge and execute a sentence all on its own accord."

In London, former Lib Dem leader Lord Ashdown suggested Mr Cameron had been left "broken-backed" by the Commons defeat and Britain was reduced as a country.

He told Sky News: "I fear as I wake up this morning that our country is a hugely, hugely diminished country.

"In more than 50 years of trying to serve my country in one form or another, I don't think I have ever felt more depressed or ashamed."

Chancellor George Osborne also admitted there would be "national soul-searching" about the UK's role on the world stage following the vote.

But Mr Cameron insisted Britain remained "deeply engaged" as he rejected the idea he would have to apologise to Mr Obama for not joining any future coalition.

Highlighting the UK's military power and diplomatic influence, he said: "We have great strengths as a country, we should continue to use those.

"But on this specific issue, because of the huge concerns about this appalling Syrian conflict and people worrying about how we might get sucked into it, on that specific issue that trumped, as it were, the sense of outrage about the chemical weapons.

"I understand that, I get that."

The Prime Minister recalled Parliament for an emergency debate and vote following the atrocity in Damascus, where more than 1,300 people are believed to have died.

Urging MPs to support possible military action against Bashar al Assad regime, he called the massacre "abhorrent" and the cause of "sickening human suffering".

Video:Syria Vote: Lord Ashdown Reaction

Mr Cameron admitted it was not possible to be 100% certain the Assad regime was behind the attack in Damascus but said he had been convinced by the evidence available.

But he was left humiliated when 39 Tory rebels and nine Liberal Democrats joined with Labour to oppose the Government and won by 285 votes to 272.

The Prime Minister had already been forced to water down his position by Labour and promise direct British involvement would require a second vote.

Education Secretary Michael Gove was heard shouting "disgrace, you're a disgrace" at coalition rebels after the result was announced.

Video:US May Act Alone Against Syria

The Scottish National Party's Westminster leader Angus Robertson told Sky News he watched as the minister had to be "persuaded to calm down".

Mr Osborne insisted it was a testament to Mr Cameron that he had gone to Parliament to ask for its consent, rather than pushing ahead.

One of the Tory rebels, former minister Crispin Blunt, also brushed off the impact on the Prime Minister's reputation as a "temporary blip".

"He has done a huge amount to repair the reputation of the institution of Parliament, having learned the lessons from Tony Blair and the experience of 2003 and Iraq," he said.

Video:Cameron Humiliated By Syria Vote

"He exposed himself to the potential for defeat last night because of the way he manages Parliament. That is to his eternal credit."